Alkali-Metal-Mediated Reversible Chemical Hydrogen Storage Using Seawater.

The economic viability and systemic sustainability of a green hydrogen economy are primarily dependent on its storage. However, none of the current hydrogen storage methods meet all the targets set by the US Department of Energy (DoE) for mobile hydrogen storage. One of the most promising routes is through the chemical reaction of alkali metals with water; however, this method has not received much attention owing to its irreversible nature. Herein, we present a reconditioned seawater battery-assisted hydrogen storage system that can provide a solution to the irreversible nature of alkali-metal-based hydrogen storage. We show that this system can also be applied to relatively lighter alkali metals such as lithium as well as sodium, which increases the possibility of fulfilling the DoE target. Furthermore, we found that small (1.75 cm 2 ) and scaled-up (70 cm 2 ) systems showed high Faradaic efficiencies of over 94%, even in the presence of oxygen, which enhances their viability.